docs: def set_dtreat_dfit(self, dfit=None):
          """ Set the fitting dictionnary
  
          A dict contaning all parameters for fitting the data
          Valid dict content includes:
              - 'type': str
                  'fft':  A fourier filtering
                  'svd':  A svd filtering
  
          """
          warnings.warn("Not implemented yet !, dfit forced to None")
          dfit = None
  
          assert dfit is None or isinstance(dfit,dict)
          if isinstance(dfit,dict):
              assert 'type' in dfit.keys()
              assert dfit['type'] in ['svd','fft']
  
          self._dtreat['dfit'] = dfit
          self._ddata['uptodate'] = False